Teacher leadership, social justice and self-efficacy are fundamental educational constructs that if collectively applied may facilitate the continuous development of pedagogical practices that bring forth academic equity and success to all students. Currently, the collective application of these constructs is critical because of the increase in diversity across socio-economic and ethnic groups among students and teachers in our educational systems. Thus, exemplary and socially just educational practices that can effectively meet the academic and professional needs of all are paramount in our educational communities. This empirical investigation assesses how mentor teachers can actively participate as pioneers for educational improvement, through their professional commitment as teacher leaders who are socially just and highly efficacious. The purpose of this study was to examine the attributes and the perceptions of teacher leadership, social justice, and self-efficacy that existed among five mentor teachers as they mentored and supported novice in-service teachers. The study used descriptive and embedded multiple case study analyses to empirically assess the strengths and areas of improvement needed among the mentor teachers related to the three constructs (teacher leadership, social justice and self-efficacy). The findings revealed that mentor teachers areas of strength appeared to be in the teacher leadership and self-efficacy constructs, and their area of improvement needed appeared to be related to the social justice construct. Further, the number of years in teaching experience was not necessarily associated with mentor teachers’ perceptions of their effectiveness in teacher leadership, social justice and self-efficacy. This study contributes to educational research with implications that social justice is a vital educational construct in which all educators should demonstrate competence while they serve as agents of socialization in educational contexts. Altogether, teacher leadership, social justice and self-efficacy are important educational constructs that if successfully applied in our educational communities, have the potential to generate exemplary pedagogical practices among mentor teachers and classroom teachers and positive academic outcomes for students.